Method of treating milling products



Patented Jul 20, 1937 UNITED STATES PATENT OFFICE Frederick H.PenmiDallas, Tex.

No Drawing. Application August 6, 1935, Serial No. 35,018

8 Claims.

My invention relates to the improving of milling products and moreparticularly has reference to the bleaching and ageing or maturing ofwheat flour and other grain and vegetable flours and edible millingproducts in general.

A present form of general milling practice comprises a treatment of theflour with chlorinecontaining gas to effect ageing thereof, therebyeliminating storage and the time element to bring about the proper andnecessary conditioning of the flour. The gases heretofore employed forthis purpose, in addition to being maturing agents, also possessbleaching properties. However, they materially injure the quality of thefiour when employed in suflicient amount to obtain a complete bleach andtherefore it is customary to use an amount of the gas not substantiallyin excess of that required to age the flour, the bleaching being securedby a subsequent treatment with bleaching agents.

In my prior application, Serial #732,536, filed June 26, 1934, of whichthis application is a continuation-impart, I have disclosed and claimeda process for ageing and bleaching milling products in dry form byadmixing therewith a solid chlorine-liberating compound, such as calciumhypochlorite, and a solid ammonium compound, these compounds reactingwith each other within the flour to form a gaseous bleaching andmaturing agent. The ammonium compounds specifically disclosed for thispurpose in my prior application referred to are the phosphate, sulphate,carbonate, persulphate, borate, chlorate, perchlorate, nitrate andnitrite, as exemplary of inorganic ammonium salts, and ammonium acetate,benzoate and citrate as illustrative of organic salts.

I have now found that the solid chlorine-liberating compounds of myprior application can be dispensed with when the flour is given thecustomary gas treatment above referred to, the flour containingsufiicient chlorine as a result of this ageing operation to react withthe ammonium The gaseous treating agents used in the present process areany of those heretofore contemplated for the ageing and bleaching ofmilling products. Suitable gases are chlorine, chlorine dioxide orchlorine peroxide, nitrosyl chloride, nitrogen trichloride and similargaseous compounds containing chlorine or both chlorine and nitrogen. Thegas treatment of the flour is effected in tumblers or closed containersin the usual manner and inasmuch as such operations are well known tothe art, detailed description thereof is here unnecessary.

The gas treatment is insufiicient to impart the desired color to thefiour since, as already indicated, the quality of the flour is degraded,if not completely ruined, by an adequate amount of the gas to effect acomplete bleach. As stated, this gas treatment is essentially for thepurpose of ,ageing or maturing the flour and if any bleaching isefiected thereby, it is only partial. However, in the present process,the gas treatment performs the additional function of chlorinating orpre-conditioning the flour for reaction with the ammonium compound.

Of the ammonium compounds mentioned, the preferred are those which aredry and free-flowing in finely divided or powdered form, such asammonium sulphate, phosphate and chloride. They should be added as soonas the flour has been gas-treated, or before or at the time of the gastreatment. Since the compounds which I employ can be prepared in finelydivided or powdered form, they can be fed into and intimately mixed withthe dry flour by means of the powder feeding devices of the type nowcommonly used in the mills and they are preferably powdered to afineness approximating that of the milling product to be treated or tosuch a degree that 75% to 95% will pass through a 300 mesh screen.

As in my prior application referred to, the oxygen-containing ammoniumsalts are preferred, particularly ammonium phosphate and ammoniumsulphate which are especially desirable since they are non-hygroscopic,dry and freefiowing in finely divided solid form and are stable andusable under the usual mill conditions.

Only minute amounts of the ammonium compound are necessary to react andform suflicient bleaching agent within the chlorinated flour to effectsatisfactory bleaching or to complete such partial bleaching as may beobtained by the gas treatment. For example,one-half ounce ammoniumphosphate or sulphate per 198 pound barrel of flour, added immediatelyafter the customary gas treatment now employed in the art, is sufficientto impart a satisfactory color to the flour after the flour has beenexposed to the action of the ammonium compound or its reaction productsfor a time period of about 12 to 18 hours. The ammonium compound, assuch, has no maturing action and therefore its addition, particularly inthe small amounts employed, presents no danger of over-treating thematured product of the gas operation.

By the term dry, as applied in the appended claims to the millingproduct, it is meant that the milling product, although containing itsnormalor usual moisture content, has not been intentionally wetted as isdone, for example, in the making of dough.

Having described my invention, I claim:

1. A method for bleaching and ageing flour and other milling productswhich comprises treating the milling product in dry form withchlorinecontaining gas and with a finely divided solid ammonium compoundcapable of and in sufiicient amount for reacting with chlorine in thepresence 01' the'milling product to form a bleaching agent, and exposingthe milling product in dry form to the action of said agent for a timeperiod adequate to efiect substantial bleaching thereof.

2. The method as defined in claim 1 further characterized in that theammonium compound is present in the milling product during the gastreatment.

3. A method for improving milling products which comprises ageing theproduct by contacting it in dry form with a chlorine-containing gas,then admixing with the dry product a finely divided solid ammoniumcompound capable of and in suificient amount for generating a bleachingag nt in the thus treated product, and exposing the milling product indry form with chlorinecontaining gas, then admixing with the dry productfinely divided solid ammonium phosphate in sufiicient amount to form ableaching agent in the thus treated product, and exposing the millingproduct in dry form to the action 01' said agent for a time periodadequate to eii'ect substantial bleaching thereof.

5. A method for bleaching and ageing flour and other milling productswhich comprises treating the milling product in dry form withchlorinecontaining gas, then admixing with the dry product finelydivided solid ammonium sulphate in suiiicient amount to form a bleachingagentin the thus treated product, and exposing the milling product indry form to the action of said agent for a time period adequate toeflect substantial bleaching thereof.

6. A method for bleaching and ageing flour and other milling productswhich comprises treating the milling product in dryform withchlorinecontaining gas, then admixing with the dry product finelydivided solid ammonium chloride in sufiicient amount to form a bleachingagent in the thus treated product, and exposing the milling product indry form to the action of said agent for a time period adequate toeflect substantial bleaching thereof. 7 D

7. A method for improving milling products which comprises ageing theproduct by contacting it in dry form with a chlorine-containing gas,then admixing with the dry product a finely divided solid,non-hygroscopic, oxygen-containing ammonium salt capable of and insuflicient amount for reacting with the chlorine content of the productto form a bleaching agent, and exposing the milling product in dry formto the action of said agent for a time period adequate to effectsubstantial bleaching thereof.

8. A method for improving milling products which comprises ageing theproduct by contacting it in dry form with a gaseous compound of chlorineand nitrogen, then admixing with the dry product a finely divided solidammonium compound capable of and in suflicient amount for generating ableaching agent in the thus treated product, and exposing the millingproduct in dry form to the action of said agent for a time periodadequate to eflfect substantial bleaching thereof.

FREDERICK H. PENN.

